Astro-1 was the first space shuttle mission dedicated exclusively to
astronomical observations since the start of shuttle flights
in 1981. When the development of the Astro telescopes was proposed in the late 1970s, many astronomers hoped that the space shuttle would provide relatively easy and vastly expanded access to space for small and moderate-sized
telescopes, such as those that were being launched on sounding rockets.
Such vehicles typically provide an experimenter with only 5 min to
collect data at high altitudes, enough to get a brief measurement of 1
or 2 bright objects. The prospect of a week or more in orbit
(actually, up to 28 days were then contemplated by NASA officials),
collecting data on hundreds of celestial objects 24 hours per day, was
more than enough of an incentive to overcome the concern that working in the
shuttle world (as it came to be known at NASA) might not be so easy for
academic scientists.

An additional attraction offered by the shuttle-attached-payload
program was the promise of multiple flights of an individual
instrument. This approach allows for repairs, modifications, and
calibrations to be performed between missions. It was also
supposed to make space science more like laboratory
experimentation and provide opportunities to train graduate
students and young scientists in the development of space hardware.
Finally, the new approach was expected to reduce the need for extremely
high-level quality assurance, and its associated costs, because
occasional instrument failures could be tolerated in a program of this
type.

More than one decade after they were conceived, the telescopes of the Astro-1 mission were finally launched aboard the space shuttle Columbia. During the mission, both of the shuttle computer terminals used by the crew to control the Astro-1 instruments overheated and had to be shut down. We recovered from these events by devising
a new operating procedure in which the
crew pointed the UV telescopes at the objects of interest with
a joy-stick control (similar to that on a simple video game) while the
ground-support team controlled the telescopes by
up-linking commands directly to the computers in the telescopes,
bypassing the malfunctioning terminals on the shuttle.

Averaged over the 7-day portion of the mission devoted to scientific
operations, HUT achieved a net observing efficiency (on-target time
divided by total clock time) of 25%, while the three other Astro
telescopes simultaneously gathered data. Comparison with other
missions reveals that this is an excellent level of efficiency for a
complex astronomical satellite in low-Earth orbit, especially
considering that only 24 hours were used for all the preparations before the observations began. During the Astro-1 mission, HUT
obtained observations of 77 different objects, with multiple
observations made of some of them, totaling nearly 40 hours. Although
only a portion of the data has now been analyzed in detail, it is
already clear that HUT and the other Astro telescopes are providing
important new insights in many branches of astronomy. Because of this
success, NASA officials have decided to conduct a second mission,
dubbed Astro-2, currently scheduled for launch in 1994.